[33.07] Down-to-Earth Astronomy: Tsunami from Asteroid-Comet Impacts

J. G. Hills, C. L. Mader, M. P. Goda, M. S. Warren (LANL)

We have begun a systematic study of tsunami
produced by the impacts of asteroids and comets on Earth. As
the first phase of this work, we have looked at tsunami
produced by the impacts of moderately large asteroids, 5-6
km in diameter, in the middle of the large ocean basins. This
work is to identify coastal areas that are most susceptible
to impact tsunami. We find that areas with gradual
continental shelves such as the British Isles in Europe
and Florida in the United States are less susceptible to
impact tsunami while regions with little continental shelf
are the more exposed. Gradual continental
shelves tend to reflect the tsunami back into the ocean.
An asteroid 5-6 kilometers in diameter hitting in mid
Atlantic would produce tsunami that would travel all the way
to the Appalachian Mountains in the upper two-thirds of the
United States; e.g., Washington, D.C. would be washed out.
In Florida, the damage would be much less except in the area
from West Palm Beach through Ft. Lauderdale to Palm Beach
where a deepwater shipping channel would funnel the tsunami
energy to shore.
In Europe, the most susceptible area is the Spain-Portugal
peninsula, which has very little continental shelf. In
retrospect, this result is not surprising as this peninsula
has been subject to earthquake tsunami during the last few
hundred years. An asteroid 5-6 kilometers in diameter
impacting between Hawaii and the West Coast would wash out
the coastal cities. The area between Los Angelos and San
Diego is particularly vulnerable. This same impact would
produce tsunami that would cover most of the land area of
Oahu, the most populous Hawaiian island.

The author(s) of this abstract have provided an email address for comments about the abstract: jgh@lanl.gov